We propose to continue and expand our surveillance of medicinal drugs for carcinogenic effects. This currently involves the follow-up of a cohort of 143,574 persons who received prescriptions from the Kaiser Permanente (KP) outpatient pharmacy in San Francisco from 1969 to 1973. Cases of cancer are detected by computer linkage with KP and California Tumor Registry records and are verified by chart review. Hypothesis-generating screening analyses are carried out and hypotheses from this and other sources are tested with case-control studies, for which records from the 1.9 million member northern California KP program are available. In the proposed 1987-1992 period we can begin to study drug effects with latency periods in the two-decade range. The new activities involve an expansion of the recently-started collection of new pharmacy data to cover about 400,000 health plan members, in order to begin to investigate possible carcinogenic effects of drugs introduced since our original pharmacy data collection. We also propose to make further valuable use of these new data by studying non-cancer adverse drug effects in both a hypothesis-generating and hypothesis-testing manner.